Process for separating saturated compounds from olefins

ABSTRACT

There is provided a process for separating olefins from saturated hydrocarbons in a feedstock containing saturated hydrocarbons, internal olefins, and alpha olefins characterized by steps of selectively forming of olefin-linear polyaromatic compound adducts and steps of dissociation of these adducts.

1. FIELD OF THE INVENTION

This invention relates to a process for separating olefins fromsaturated hydrocarbons followed by separating linear alpha olefins andinternal olefins from a saturated hydrocarbon stream and from an olefinstream.

2. BACKGROUND OF THE INVENTION

Many industrial processes produce olefin/saturated hydrocarbon streamsthat are mixtures of olefins, saturated hydrocarbons, and oxygenates.Olefins are frequently used in the manufacture of polymers such aspolyethylene, as drilling mud additives, or as intermediates for theproduction of oil additives and detergents. Some industrial processesmanufacture olefins streams by oligomerizing ethylene over an alphaolefin catalyst to produce mixtures of alpha and internal olefins havinga broad range of carbon numbers. However, these streams rely on the useof ethylene as a feedstock material, which add a significant cost to themanufacture of the olefin. On the other hand, the FT process starts withan inexpensive feedstock, syngas, generally derived from natural gas,coal, coke, and other carbonaceous compounds to make oligomers comprisedof olefins, aromatics, saturates, and oxygenates.

The FT process, however, is not very selective to the production ofolefins. While reaction conditions and catalysts can be tuned tomanufacture a stream rich in the desired species within the FT productstream, a large percentage of the FT stream contains other types ofcompounds which must be separated from the olefins, which olefins arepurified, and then sold into different markets. For example, a typicalcommercial FT stream will contain a mixture of saturated hydrocarbons,olefins, aromatics, and oxygenates such as organic carboxylic acids,alcohols, ethers, esters, ketones, and aldehydes. All these compoundsmust be separated from the crude FT stream before a particularcomposition may be offered commercially. To further complicate theseparation operation, the FT stream contains compounds having a widespectrum of carbon numbers, as well as a wide variety of olefins,ranging from C₂-C₂₀₀ species, internal linear olefins, alpha linearolefins, internal branched olefins, alpha branched olefins, and cyclicolefins, many of which have similar molecular weights. Separating andisolating these species is no easy task. Conventional distillationmethods are frequently inadequate to separate species having closelyrelated boiling points.

Various processes have been proposed to efficiently separate thedifferent species in a FT stream with sufficient purity that aparticular composition is acceptable in the intended application. Theseprocesses for separating out different species in a FT stream includethe use of molecular sieves, which are restricted to a feed have anaverage carbon number range which is more limited than a compositioncontaining a broad spectrum of average carbon numbers ranging fromC₅-C₂₀, to the use of exchange resins, to the use of super-fractionatersoften operated at high pressure, and the use of oligomerizationcatalysts or etherification techniques to alter the boiling points ofthe species in the FT stream. Many reactive methods for separatingspecies in a FT stream do not, however, selectively react with olefinswhile simultaneously reject paraffins.

U.S. Pat. No. 4,946,560 described a process for the separation ofinternal olefins from alpha olefins by contacting a feedstock with anadducting compound such as anthracene to form an olefin adduct,separating the adduct from the feedstock, dissociating the olefin adductthrough heat to produce anthracene and an olefin composition enriched inalpha olefin, and separating out the anthracene from the alpha olefin.This reference does not suggest the desirability or the capability ofanthracene to separate olefins from saturated hydrocarbons in a firststep, or further separate the linear alpha olefins from the saturatedhydrocarbons removed in the first step along with separating linearalpha olefins from an olefin stream removed in the first step.

As used throughout the specification and claims, the words, “first,second, third, etc” are meant only to distinguish one feed, composition,compound, or reaction zone, etc., from a different feed, composition,compound, reaction zone, etc., and are not meant to designate aparticular sequence. For ease of tracking a particular stream and forconvenience sake only, olefin streams have been assigned the letter “o,”alpha olefin streams have been assigned the letters “ao,” internalolefin streams have been assigned the letters “io,” and saturatedcompound streams have been assigned the letter “s.” Their presence doesnot imply a particular order, sequence, or ascribe a meaning to thedescription and claim language, nor does a letter's absence in a claimor embodiment imply that a process step or composition not expresslymentioned is required or implicit in the embodiment or claim. Where nospelled number or assigned letter is present, its use is not deemednecessary since other compounds, composition, steps, or reaction zonesare not identically expressed in the embodiment or claim. Their absenceor presence do not modify or ascribe a particular meaning, other than todifferentiate from other identically expressed compounds, compositions,steps, reaction zones, etc in the embodiment or claim.

3. SUMMARY OF THE INVENTION

This invention relates to a process for separating and isolating speciesin a FT stream. There is provided a process for treating a feedstockcomprising saturated hydrocarbons, internal olefins, and alpha olefins,comprising:

a) contacting the feedstock with a linear polyaromatic compound in afirst reaction zone under conditions effective to form a reactionmixture comprising first linear polyaromatic compound-olefin adducts andsaturated hydrocarbons;

b) separating said olefin adducts from the saturated hydrocarbons in thereaction mixture to form a first olefin adduct stream and a firstsaturated hydrocarbon stream;

si) contacting at least a portion of the first saturated hydrocarbonstream with a linear polyaromatic compound in a second reaction zoneunder conditions effective to form a reaction mixture comprising asecond linear polyaromatic compound-olefin adduct and saturatedhydrocarbons;

sii) separating said second olefin adduct from the reaction mixture inthe second reaction zone to form a second olefin adduct stream and asecond saturated hydrocarbon stream, wherein the concentration of thesaturated hydrocarbons in the second saturated hydrocarbon stream isenriched over the concentration of saturated hydrocarbons in the firstsaturated hydrocarbon stream, and the concentration of the saturatedhydrocarbons in the first saturated hydrocarbon stream is enriched overthe concentration of saturated hydrocarbons in the feedstock; and

oi) dissociating said first olefin adducts to form linear polyaromaticcompounds and a first olefin composition comprising alpha olefins andinternal olefins;

oai) contacting the olefin composition with a linear polyaromaticcompound in a third reaction zone under conditions effective to form areaction mixture comprising linear polyaromatic compound-alpha olefinadducts and an internal olefin composition;

oaii) separating said alpha olefin adducts, and optionally unreactedlinear polyaromatic compounds as well, from the reaction mixture in thethird reaction zone to form an alpha olefin adduct stream and aninternal olefin stream;

oaiii) dissociating the alpha olefin adducts to form linear polyaromaticcompounds and an alpha olefin composition;

whereby the concentration of alpha olefins in the alpha olefincomposition is enriched over the concentration of alpha olefins in thefirst olefin composition, and the concentration of alpha olefins in thefirst olefin composition is enriched over the concentration of alphaolefins in the feedstock.

4. BRIEF DESCRIPTION OF THE DRAWING

The FIGURE depicts a block flow diagram in which the adduction,separation, and dissociation steps occur in each of the individualblocks 1, 2, and 3, and lines 1-8 represent the feed and product streamsinto and from each block.

5. DETAILED DESCRIPTION OF THE INVENTION

As used throughout this specification and in the claims, the term“comprising” means “at least,” such that other unmentioned elements,ingredients, or species are not excluded from the scope of invention.

The feed stream to be treated comprises at least olefins and saturatedhydrocarbons. The class of saturated hydrocarbons as used hereinincludes at least a paraffin. The class of saturated hydrocarbons mayalso include other molecules such as cycloparaffins.

An olefin means any compound containing at least one carbon—carbondouble bond. The olefins may be linear, branched, conjugated, containmultiple double bonds anywhere along the chain, substituted,unsubstituted, contain aryl or alicyclic groups, or contain heteroatoms.

The olefins may contain aryl moieties along with an aliphatic orcycloaliphatic moiety within the same compound, or may consist solely ofan aliphatic, cycloaliphatic, or cycloaliphatic with aliphatic moietieson the compound. Preferably, the olefin is an aliphatic compound.

The olefin may be branched or linear. Examples of branching includealkyl, aryl, or alicyclic branches. The number of unsaturation pointsalong the chain is also not limited. The olefin may be a mono-, di-,tri-, etc. unsaturated olefin, optionally conjugated. The olefin mayalso contain acetylenic unsaturation.

An alpha olefin is an olefin whose double bond is located on both of αand β carbon atoms. An α carbon atom is any terminal carbon atom,regardless of how long the chain is relative to other chain lengths in amolecule. The alpha olefin may be linear or branched. Branches orfunctional groups may be located on double bond carbon atoms, on carbonatoms adjacent to the double bond carbon atoms, or anywhere else alongthe carbon backbone. The alpha olefin may also be a polyene, wherein twoor more points of unsaturation may be located anywhere along themolecule, so long as at least on double bond is in the alpha position.

An internal olefin(s) is an olefin whose double bond is located anywherealong the carbon chain except at any terminal carbon atom. The internalolefin may be linear or branched. The location of a branch orsubstitution on the internal olefin is not limited. Branches orfunctional groups may be located on the double bond carbon atoms, oncarbon atoms adjacent to the double bond carbon atoms, or anywhere elsealong the carbon backbone.

The olefin may also be substituted with chemically reactive functionalgroups. These types of compounds are identified as oxygenates. Examplesof chemically reactive functional groups are carboxyl, aldehyde, keto,thio, ether, hydroxyl, and amine. The number of functional groups on amolecule is not limited. The functional groups may be located anywherealong the carbon backbone.

The feedstock is generally produced by commercial processes such as theoligomerization of ethylene, optionally followed by isomerization anddisproportionation. Alternatively, the feedstock may be produced by theFisher-Tropsch process, which typically contains a high proportion ofparaffins. A Fisher-Tropsch process catalytically hydrogenates CO toproduce compositions containing aliphatic molecular chains. Otherprocesses for making feedstocks which may contain mixtures of olefinsand paraffins include the dehydrogenation of paraffin, such as thosemade by the Pacol™ processes of UOP, and the cracking of waxes. The mostpreferred feedstock is that obtained from a Fisher-Tropsch (FT)synthesis.

FT catalysts and reaction conditions can be selected to provide aparticular mix of species in the reaction product stream. For example,the particular catalyst and reaction conditions may be tuned to enhancethe amount of olefins and decrease the amount of paraffins andoxygenates in the stream. Alternatively, the catalyst and reactionconditions may be tuned to enhance the amount of paraffins and decreasethe amount of olefins and oxygenates in the stream.

Generally, the reaction conditions will vary depending on the type ofequipment employed. The FT reaction temperatures vary between 100° C. to500° C., an inlet gas pressure to the reactor from atmospheric to 1500psig, and an H₂/CO ratio from 0.5:1 to 5:1, preferably from 1.8:1 to2.2:1, and gas hourly space velocity ranging from 1 to 10,000 v/v/hour.A variety of reactor vessel configurations can be used, including afluidized(entrained) bed, a fixed bed, and a slurried bed. Thetemperature in these beds can be adjusted by those of ordinary skill tooptimize the formation of FT products, including hydrocarbons, andparticularly, olefins and types of olefins. To illustrate withoutlimitation, in fluidized (entrained) bed(s), the temperature of reactionis generally high—e.g. ranging from 280° to 350° C., preferably 310° to340° C.. If a fixed bed reactor(s) is used, the reaction temperature isgenerally ranges within 200° C. to 200° C., preferably between 210° and240° C., and when a slurry bed reactor(s) is used, the temperature isgenerally within the range of 190° C. to 270° C..

The catalyst used in the FT process is any known in the art, butpreferably from among Mo, W, and Group VIII compounds, including iron,cobalt, ruthenium, rhodium, platinum, palladium, iridium, osmium,combinations of the foregoing, combinations with other metals, and eachbeing in the free metal form or as alloys, or as an oxide or carbide orother compound, or as a salt. Iron based and cobalt based catalysts havefound common commercial use, and ruthenium has gained importance as ametal for the catalyst which favors the formation of high melting waxyspecies under high pressure conditions. Those of skill in the artrecognize which catalysts and combinations will favor the manufacture ofdesired species in the FT reaction composition. For example, fused ironcontaining a promoter such as potassium or oxides on a silica, alumina,or silica-alumina support are known as FT synthetic catalysts. Anotherexample is the use of Co metal. Cobalt has the advantage of producingless methane during synthesis over the older nickel based catalysts, andproduces a wide spectrum of species. With the proper selection ofsupports, promoters, and other metal combinations, the cobalt catalystcan be tuned to manufacture a composition rich in the desired species.Other catalysts, such as iron-cobalt alloy catalysts, are known fortheir selectivity toward olefins under certain process conditions.

The catalysts may be fused or precipitated, or sintered, cemented,impregnated, kneading or melting onto a suitable support.

The catalysts may also contain promoters to promote the catalyst'sactivity, stability, or selectivity. Suitable promoters include alkalior alkaline earth metals, in free or combined form as an oxide,hydroxide, salt, or combinations thereof.

A FT stream generally contains virtually no sulfur or nitrogencompounds, which may be deleterious to other catalysts which derivatizethe olefins or catalyze the reaction of olefins in other oligomerizationor polymerization processes. Regardless of the method used, however, theFT process is not very selective to a particular species, and yields awide variety of species within a composition.

Examples of some of the species found in any FT stream include paraffinshaving a broad spectrum of molecular weights, alcohols, acids, ketones,and aldehydes, and small amounts of aromatics. The linear polyaromaticcompound used in the process of the invention, however, is particularlywell adapted for the separation of olefins from saturated hydrocarbonsin a FT stream in the presence of oxygenates since oxygenates do notsignificantly impair the performance of the linear polyaromaticcompound.

While reference is made to a FT stream, it is to be understood that anystream made by any process containing olefins and saturated hydrocarbonsare suitable feedstocks for the process of the invention. Most crude FTstreams contain from 5% to 95% olefins, the remainder being saturatedhydrocarbons comprising paraffins and cycloparaffins, and optionallyother compounds such as aromatics optionally containing saturated orunsaturated alkyl branches, and oxygenates, based on the weight of allingredients in the feedstock stream to the process of the invention. Thepreferred amount of olefin present in the FT stream ranges from 15 wt. %to 70 wt. %, based on the weight of the FT stream. The amount of linearalpha olefin in the FT stream is not limited, but preferably ranges from15 wt. % to 65 wt. %, based on the weight of the FT stream. The amountof other olefins, including branched olefins and internal olefins, bothlinear and branched, is also not limited, but preferably ranges from 1wt. % to 55 wt. %, more typically from 5 wt. % to 45 wt. %, based on theweight of the FT stream. The amount of paraffin in most FT streams rangefrom 5 wt. % to 99 wt. %. In some FT streams, the FT catalyst is tunedto enhance the olefin concentration and decrease the paraffinconcentration. In these streams, the amount of paraffin generally rangesfrom 5 to 65 wt. % of the stream. In other FT streams where the FTcatalyst is tuned to enhance the amount of paraffin, the amount ofparaffin in the stream ranges from 65 wt. % to 99 wt. %. The amounts ofother compounds in a FT stream, such as oxygenates and aromatics, makeup most of the remainder of the FT stream, and are generally present inamounts ranging from 5 wt. % to 40 wt. %. Minor amounts of otherby-products and impurities, less than 5 wt. %, may be present in most FTstreams. A FT stream which consists essentially of paraffins, olefins,aromatics and oxygenates can include such minor amounts of otherby-products and impurities.

The feedstock may be a processed FT stream which has been fractionatedand/or purified by a conventional distillation, extraction, or otherseparation operation to obtain a desired carbon number cut, including acomposition containing a mixture of carbon numbers or a single carboncut composition, and to remove high and low boiling compounds, includingolefins, paraffins, aromatics, and oxygenates from the crude stream.When the separation operation is conducted by distilling the reactionmixture containing the adduct, it is preferred that the feedstock usedin the process of the invention contain an average carbon number rangingfrom C₅-C₂₀ and wherein the predominant olefin species in the feedstockis within the range of C₅-C₂₀, inclusive. The polyaromatic adductingcompound efficiently separates the saturated hydrocarbons from theolefins when the average carbon number of the feedstock and thepredominant olefinic species is within this range, inclusive. When theaverage carbon number of the feedstock exceeds C₂₀, the polyaromaticcompound-olefin adduct boils at a lower temperature than many of thespecies in the C₂₀+ feedstock composition, thereby leaving these highboiling species in the reaction mixture bottoms containing the adduct.Accordingly, the particular polyaromatic compound and the particularfeedstock composition should be so selected that the polyaromaticcompound-olefin adduct composition in the reaction mixture boils at ahigher temperature than the amount of unreacted paraffin species in thefeedstock one desires to separate. Therefore, in this preferredembodiment, the feedstock stream is one which contains an average carbonnumber ranging from C₅-C₂₀, and more preferably ranging from C₆-C₁₈, andwherein the predominant olefin species is within these ranges,inclusive. These types of FT streams are generally processed by one ofthe techniques identified above to substantially remove cuts containingingredients below or exceeding the range of C₅-C₂₀.

In addition to mixtures of olefins within this range, one may alsoemploy what are known as single carbon cuts of olefins as feedstocks,wherein the single cut is within this range. For example, the feedstockemployed may be a single C₆, C₈, C₉, C₁₀, C₁₁, C₁₂, C₁₄, or C₁₆ carboncut. These carbon cuts have utility as comonomers for polyethylene, PAO,alpha olefin sulfonates, and as drilling fluids.

In the event that one desires to employ a feedstock outside of the rangeof C₅-C₂₀, other separation techniques can be used to separate theadduct from the unreacted reaction mixture, including the selection ofhigher boiling polyaromatic compounds and/or other separation techniquessuch as liquid/liquid extraction or crystallization. These techniques,of course, can also be used with feedstocks within the range of C₅-C₂₀,inclusive.

The linear polyaromatic compound is utilized in the instant process toform the adduct with the olefins in the feed stream. As used herein,“linear polyaromatic compound” refers to a linear polyaromatic compoundhaving at least three fused aromatic rings, which may be unsubstitutedor substituted and possess similar adducting properties as theunsubstituted molecule, and mixtures thereof. The linearity shouldextend to at all three of the fused rings if a three fused ring compoundis used and to at least four consecutively fused cyclic rings if a fouror more fused ring compound is used. The linear polyaromatic compoundalso refers to mixtures of compounds containing as one of theiringredients the linear polyaromatic compound, including but not limitedto coal tars, anthracene oil, and any crude mixtures containing cutsseparated from naphthalene. The linear polyaromatic compound alsoincludes aromatic molecules linked together by a bridging group, such asa hydrocarbon chain, an ether linkage, or a ketone group containingchain so long as at least three fused rings are present in a lineararrangement; as well as those containing a heteroatom which do notinterfere in the separation of olefins from saturated hydrocarbons.

The linear polyaromatic compound has a preferential selectivity towardadducting with linear alpha olefin compounds, and secondly with otherolefins, and last with paraffins, with which the compound is virtuallyunreactive under any operating condition outside of cracking conditions.The linear polyaromatic compound of choice is one which has aselectivity for linear alpha olefin compounds over other olefins greaterthan 1:1 by mole, preferably 2:1 or more, more preferably 4:1.

Non-limiting examples of the linear polyaromatic compound includeanthracene, 2,3-benzanthracene, pentacene, and hexacene. Suitableexamples of substituents on substituted linear polyaromatic compoundsinclude, but are not limited to, lower alkyl, e.g., methyl, ethyl,butyl; halo, e.g., chloro, bromo, fluoro; nitro; sulfato; sulfonyloxy;carboxyl; carbo-lower-alkoxy, e.g., carbomethoxy, carbethoxy; amino;mono- and di-lower-alkylamino, e.g., methylamino, dimethylamino,methylethylamino; amido; hydroxy; cyano; lower-alkoxy, e.g., methoxy,ethoxy; lower-alkyanoyloxy, e.g., acteoxy; monocyclic aryls, e.g.,phenyl, xylyl, toluyl, benzyl, etc. The particular substituent size,their number, and their location, should be selected so that they arerelatively inert under the reaction conditions and not so large as toblock the formation of the Diels-Alder adduct. Suitable substitutedlinear polyaromatic compounds can be determined by routineexperimentation. Examples of suitable linear polyaromatic compoundsinclude 9,10-dimethylanthracene, 9,10-dichloroanthracene,9-methylanthracene, 9-acetylanthracene, 9-(methylaminomethyl)anthracene,2-choloranthracene, 2-ethyl-9,10-dimethoxyanthracene, anthrarobin, and9-anthryl trifluoromethyl ketone. The preferred linear polyaromaticcompounds are anthracene and 2,3-benzanthracene.

In a first reaction zone in step a), the feedstock composition,preferably a FT feedstock stream having an average carbon number rangingfrom C₆-C₁₈, is contacted with a linear polyaromatic compound. In thesecond reaction zone, the saturated hydrocarbon stream removed from thefirst reaction zone is also contacted with a linear polyaromaticcompound. In each reaction zone, the Diels-Alder adduct forming reactionis carried out in a conventional fashion. Examples of suitable equipmentin which the reactions are carried out include a continuously stirredtank reactor, configured as a single unit, in parallel, or in series,wherein feedstock or an olefin composition, and linear polyaromaticcompound, are added continuously to a stirred tank to form a liquidreaction mixture under heat, and the reaction mixture is continuouslywithdrawn from the stirred tank. Alternatively, the reaction may becarried out in a plug flow reactor or a series of plug flow reactors, abubble column, or in a batch reactor.

The feedstock and olefin composition adducting reactions are typicallycarried out over a range of temperatures from about 150° to about 290°C., preferably from about 200° to about 280° C., and most preferablyfrom about 240° to about 265° C. The adduction reaction temperature mayexceed 290° C. so long as the temperature is below the boiling point ofthe olefin under the reaction conditions. Pressures typically run fromabout atmospheric to about 100 atmospheres. The reactions can be carriedout in the gas phase under vacuum or liquid phase or mixed gas-liquidphase, depending on the volatility of the feedstock, but generally inthe liquid phase.

Stoichiometric ratios or an excess of either olefin or linearpolyaromatic compound can be used to form the adducts. The molar ratioof olefin to linear polyaromatic compound is preferably from 0.25:1 upto 10:1. Preferably, a molar excess of linear polyaromatic compounds areused to ensure a complete and large recovery of all olefins in the firstadduction zone. In succeeding adducting reaction zones where greaterselectivity towards forming adducts with linear alpha olefins aredesired, the molar ratio of linear polyaromatic compounds to olefins maybe moderated, desirably closer towards a 1.5:1 to 0.5:1 molar ratio ofolefin to linear polyaromatic compound.

The residence time is for a time sufficient to adduct the desired amountof linear polyaromatic compound with the olefin. Typical residence timesrange from 30 minutes to 4 hours in a batch reaction.

An inert solvent can be utilized to dissolve the feedstock olefins orthe linear polyaromatic compound or both in each of the adductingreactors. Preferred solvents are the hydrocarbon solvents which areliquid at reaction temperatures and in which the olefins, linearpolyaromatic compound and olefin-linear polyaromatic compound adductsare soluble. Illustrative examples of useful solvents include thealkanes such as pentane, iso-pentane, hexane, heptane, octane, nonane,and the like; cycloalkanes such as cyclopentane, cyclohexane, and thelike; and aromatics such as benzene, toluene, ethylbenzene,diethylbenzene, and the like. The amount of solvent to be employed canvary over a wide range without a deleterious effect on the reaction.

Preferably, the adducting reactions are carried out in the absence of asolvent, thereby improving the rate of reaction and avoiding the needfor additional equipment and process steps for separating the solvent.

After formation of the linear polyaromatic compound-olefin adduct instep a), the adduct stream flows to a separation vessel effective forseparating the saturated hydrocarbons from the linear polyaromaticcompound-olefin adduct to form a saturated hydrocarbon stream and anolefin adducted stream in step b). Due to the large molecular weight andstructural difference between the adducts and the other ingredients inthe reaction mixtures, such as saturated hydrocarbons and internalolefins, conventional separation techniques are quite suitable forremoving the unreacted saturated hydrocarbons in step b). For example,the saturated hydrocarbons in step b) may be removed at the overhead orin fractions, by partial vacuum or flash distillation of the reactionmixture, while simultaneously withdrawing the liquid bottoms of theseparation vessel comprising the adducts and unreacted linearpolyaromatic compounds. It is desirable to raise the temperature at thebottoms of the distillation column sufficient to retain the bottoms inliquid state, while keeping the temperature and residence time as low aspossible to avoid dissociating the adducts. Suitable temperatures at thebottoms of the separation vessel range from 210° C. to 280° C., morepreferably from 230° C. to 270° C. While the pressure is notparticularly limited, and the separation can be conducted underatmospheric pressure, it is preferred to conduct the separation underslight vacuum, e.g. 200 mmHg to 700 mmHg, to reduce the operatingtemperature and the residence time within the separation vessel. Theresidence time within the vessel should be short to avoid excessivedissociation of the adducts, such as from 1 to 30 minutes.

In step b), the unreacted saturated hydrocarbon stream distillateincludes paraffins and may include, if present in the feedstockcomposition, aromatics and oxygenates such as the alcohols, ketones,acids, along with internal and branched olefins which failed to adductwith the linear polyaromatic compound.

Alternatively, the adducts may be separated by cooling the reactionmixture until the adduct crystallizes out, followed by filtration orcentrifugation to remove the unreacted saturated hydrocarbons in stepb).

In most cases, any unreacted linear polyaromatic compound will separateout with the first adducted olefin stream. Other ingredients, such assmall amounts of higher molecular weight unreacted olefins, internalolefins, and branched olefins, may remain in the first adducted olefinstream.

The process of the invention affords the flexibility for adjusting therecovery of a stream at each adducting and separation step to optimizethe desired stream yield and concentration of species in the desiredstream. For example, if one desires an alpha olefin stream highlyconcentrated in linear alpha olefin, the recovery of olefins from thefeedstock will be moderate to avoid entraining excessive amounts ofother olefins, part of which would otherwise be entrained in successiveseparations and dilute the linear alpha olefin concentration. Highlyconcentrating the linear alpha olefins, however, results in a lowerlinear alpha olefins stream yields than could be had if the recovery ofolefin levels from the feedstock were set higher. On the other hand, ifthe linear alpha olefin stream yield is more desirable than attaininghigh concentrations of linear alpha olefins in the linear alpha olefinstream, then the recovery of olefins from the feedstock should be set ahigh level to ensure that larger quantities of olefins, including linearalpha olefins, are entrained in the olefin composition during theseparation step, thereby resulting downstream in a larger alpha olefinstream yield, but at lower alpha olefin concentrations.

The recovery of a stream in a separation operation is determined by themolar ratio of linear polyaromatic compound to olefins, the adductingresidence time, the temperature within the separation vessel, and mostimportantly, the residence time (rate of separation) of the reactionmixture in the separation vessel. To obtain a large olefin compositionrecovery, any one or a combination of the following variables areadjusted: a high linear polyaromatic compound to olefin molar ratio,e.g., >1, long residence times to ensure complete adduction, andmoderate distillation temperatures to avoid dissociating the adducts. Toobtain a smaller olefin composition recovery and highly concentrate thelinear alpha olefins in the linear alpha olefin composition, any one ora combination of the following variables are adjusted: close to a 1:1molar ratio or less, of linear polyaromatic compounds to olefins in thefeedstock and shorter residence times to selectively adduct the linearalpha olefins in the feedstock. In either case, however, theconcentration of the linear alpha olefin, or any other desired species,is enriched in the ultimate stream compared to the concentration oflinear alpha olefin, or the other desired species, in the precedingcomposition treated and in the feedstock.

The rate of olefin recovery from the feedstock is not limited, andgenerally will depend upon the amount of olefin present in thefeedstock. In one embodiment, the rate of recovery of olefin adductsfrom the first separation vessel, in moles/unit time, range from 0.10 to0.40, more preferably from 0.15 to 0.35, each based upon a feedstockrate of 1.00. At these rates, from 40% to 100% of the olefins in thefeedstock may be recovered into the olefin composition. In anotherembodiment, the rate of recovery ranges from 0.20 to 0.30, based upon afeedstock rate of 1.00.

In general, when a highly concentrated linear alpha olefin compositionis desired, from 40% to 70% of the linear alpha olefins in the feedstockmay be recovered into the olefin composition, and when the emphasis ison quantity of linear alpha olefin with a slight reduction in linearalpha olefin concentration in the linear alpha olefin stream, therecovery of olefins from the feedstock ranges from 70% to 100%. As notedabove, in either case, the concentration of the desired species in theultimate stream will be enriched over the concentration of the desiredspecies in preceding feeds.

Based on the above as an example of optimizing the concentration or thequantity of linear alpha olefins in an alpha olefin stream, those ofordinary skill can set the rates of recovery and percentage of a desiredspecies recovered at each separation step to optimize the concentrationor quantity of other species in the feedstock one desires to recover.

When the saturated hydrocarbons are separated from the linearpolyaromatic compound-olefin adduct in the separation vessel as a firstsaturated hydrocarbon stream, the first saturated hydrocarbon stream isenriched in its concentration of saturated hydrocarbons over theconcentration of saturated hydrocarbons in the feedstock flowing to thefirst adduct reaction zone, and the concentration of olefins in thefirst saturated hydrocarbon stream is reduced over the concentration ofolefins in the feedstock entering the first adduct reaction zone.

In the next step of the process, step si), the first saturatedhydrocarbon stream comprising an enriched concentration of saturatedhydrocarbons and a reduced concentration of linear alpha olefins andinternal olefins, is contacted with linear polyaromatic compounds in asecond adducting reaction zone under conditions effective to form areaction mixture comprising second linear polyaromatic compound-olefinadducts and an second saturated hydrocarbon composition. Suitablereaction conditions and vessels include those used in the adductingreaction zone for the feedstock.

Once the second linear polyaromatic compound-olefin adduct has beenformed in the second reaction zone in step si), the adduct stream flowsto a separation vessel in step sii) effective for separating the secondlinear polyaromatic compounds-olefin adducts from the saturatedhydrocarbons to form a second saturated hydrocarbon stream enriched inthe concentration of saturated hydrocarbons over the concentration ofsaturated hydrocarbons in the first saturated hydrocarbons stream, and asecond linear polyaromatic compound-olefin adduct stream.

Suitable methods and conditions for separating the second adducts fromthe second reaction mixture include any of the methods used to removethe adducted olefins from the reaction mixture in the first separationzone. Preferably, the second reaction mixture is distilled and a secondsaturated hydrocarbon stream is removed at the overhead of thedistillation column, while the olefin adducts are removed from thecolumn as a liquid bottoms stream. The second saturated hydrocarbonstream includes some internal olefins and alpha olefins, but in reducedconcentrations over the concentration of these species in the firstsaturated hydrocarbon stream. However, the concentration of thesaturated hydrocarbons in the second saturated hydrocarbon stream isenriched over their concentration in the first saturated hydrocarbonstream.

The second linear polyaromatic compound-olefin adducts in the secondolefin adduct stream removed from step sii) are optionally, butpreferably dissociated in step siii) in a dissociation zone to formlinear polyaromatic compounds and a second olefin composition. Thedissociation process can be accomplished by feeding the adducted olefinstream to a dissociation vessel where the adducted olefin stream isheated and pyrolyzed at a temperature ranging from about 200° to about500° C., preferably from about 300° to about 350° C., for a timesufficient to dissociate the adducts. The dissociation temperature canbe further reduced below 200° C. by stripping olefin gas as it isliberated using an inert gas. The pyrolysis frees the olefins from thelinear polyaromatic compound. One or more dissociation vessels may beused in series to conduct the dissociation, and the dissociation vesselsmay also be operated under a partial vacuum up to superatmosphericpressures.

In an optional but preferable step siv), the linear polyaromaticcompound may subsequently be separated from the resulting mixture by anyconventional means, which may occur simultaneously with the pyrolysisoperation in the same pyrolysis equipment, such as by vacuum or flashdistilling off the olefins along with any impurities at the pyrolysistemperatures, and removing the linear polyaromatic compound as a bottomsfrom the dissociation zone. The dissociation vessel is operated underslight vacuum to lower the boiling point of the dissociated linear alphaolefin and at a temperature sufficient to dissociate the adduct. Otherseparation techniques include filtration and centrifugation.

The linear polyaromatic compounds may be recycled back to the firstadducting reaction zone or to a mixing zone wherein the feedstock,linear polyaromatic compound recycle, and some fresh linear polyaromaticcompound are premixed prior to entering the adduct reaction zone.

The first olefin adduct stream, preferably removed from the separationvessel in step b) as a liquid bottoms stream, is dissociated in step oi)in a dissociation zone to form linear polyaromatic compounds and a firstolefin composition. The equipment and processing conditions forconducting the dissociation of the first olefin adduct stream may be thesame equipment and processing conditions used to dissociate the secondolefin adduct stream. For example, the dissociation process can beaccomplished by feeding the adducted olefin stream to a dissociationvessel where the adducted olefin stream is heated and pyrolyzed at atemperature of from about 200° to about 500° C., preferably from about300° to about 350° C., for a time sufficient to dissociate the adducts.The dissociation temperature can be further reduced below 200° C. bystripping olefin gas as it is liberated using an inert gas. Thepyrolysis frees the olefins from the linear polyaromatic compound. Oneor more dissociation vessels may be used in series to conduct thedissociation, and the dissociation vessels may also be operated under apartial vacuum up to superatmospheric pressures.

In an optional step oii), the linear polyaromatic compound is separatedfrom the resulting reaction mixture by any conventional means, which mayoccur simultaneously with the pyrolysis operation, such as by vacuum orflash distilling off the olefins along with any impurities at thepyrolysis temperatures, and removing the linear polyaromatic compound asa bottoms from the dissociation zone. The dissociation vessel isoperated under slight vacuum to lower the boiling point of thedissociated linear alpha olefin and at a temperature sufficient todissociate the adduct. Other separation techniques include filtrationand centrifugation.

In this case, one may further optionally recycle the linear polyaromaticcompound removed from the dissociation zone to the first adducting zone,wherein the dissociated linear polyaromatic compounds become a source ofthe linear polyaromatic compounds used for the adducting reaction in thefirst adducting zone, optionally with a fresh source of linearpolyaromatic compound derived from linear polyaromatic compoundsobtained from separation operations elsewhere in the process or fromvirgin stock.

The first olefin composition, whether separated or in mixture with thedissociated linear polyaromatic compounds, is now enriched in theconcentration of olefins over the concentration of olefins in thefeedstock. Since the linear polyaromatic compound exhibits a preferencetowards adducting with linear alpha olefins, the linear alpha olefinconcentration in the olefin composition is enriched over theconcentration of linear alpha olefins present in the feedstock, based onthe weight of all ingredients in the feedstock and the olefincomposition. In the event that the olefin composition is not separatedfrom the linear polyaromatic compounds prior to feeding the olefincomposition to the AO adducting reaction zone, the concentration of theingredients in the olefin composition exclusive of the weight and amountof linear polyaromatic compounds, is enriched over the concentration ofolefins in the feedstock composition. Further, the concentration ofsaturated hydrocarbons and the concentration of paraffins in the olefincomposition is reduced over that of the feedstock.

In the next step of the process, step oai), the first olefin compositionis contacted with linear polyaromatic compounds in an AO reaction zoneunder conditions effective to form a reaction mixture comprising linearpolyaromatic compound-alpha olefin adducts and an internal olefincomposition. Suitable reaction conditions and vessels include those usedin the adducting reaction zone for the feedstock. Since the first olefincomposition used as the feed is essentially, if not completely, free ofsaturated hydrocarbons which would otherwise have an effect of dilutinga feedstock, the conversion of olefins in the first olefin compositiontoward linear polyaromatic compound-linear alpha olefin adducts ishigher than the conversion of the feedstock toward linear polyaromaticcompound-linear alpha olefin adducts. The preferential selectivity ofthe linear polyaromatic compound toward linear alpha olefins makespossible the separation between the linear alpha olefins and otherspecies in the olefin composition, such as linear internal olefins,branched internal olefins, and branched alpha olefins.

Once the third linear polyaromatic compound-linear alpha olefin adducthas been formed in the AO reaction zone in step oai), the third adductstream flows to a third separation vessel in step oaii) effective forseparating the internal olefins and other unreacted olefins from thelinear polyaromatic compound-alpha olefin adducts to form an internalolefin stream and an alpha olefin adducted stream. Suitable methods andconditions for separating the adducts from the reaction mixture includeany of the methods used to remove the adducted olefins from the reactionmixture in the first separation zone. Preferably, the reaction mixtureis distilled and the internal olefin stream is removed at the overheadof the distillation column, while the linear alpha olefin adducts areremoved from the column as a liquid bottoms stream. The separatedunreacted internal olefin stream distillate contains some linearinternal olefins, branched internal olefins, and branched alpha olefins.The concentration of the linear internal olefins, branched internalolefins, and branched alpha olefins in the internal olefin stream isenriched over the concentration of these olefins in the first olefincomposition and in the feedstock.

The rate of recovery of linear alpha olefin adducts in the separationvessel of step oaii) is also variable and not limited. In general, thepercentage of linear alpha olefin recovered from the olefin compositionis set such that from a total of 30 to 60% linear alpha olefins arerecovered into the alpha olefin stream, based upon the amount of linearalpha olefin present in the feedstock. If emphasis is placed uponrecovering larger amounts of linear alpha olefin into the alpha olefinstream, the percentage of linear alpha olefin recovered from the olefincomposition is set such that from a total of greater than 60% to 95%linear alpha olefins based upon the amount of alpha olefins in thefeedstock are recovered into the alpha olefin stream.

The linear polyaromatic compound-alpha olefin adducts in the alphaolefin adduct stream removed from step oaii) are dissociated in stepoaiii) in a dissociation zone to form linear polyaromatic compounds andan alpha olefin composition. Suitable methods and conditions fordissociating the adducts in the alpha olefins adduct stream include anyof the methods mentioned as suitable for dissociating the adducts in thefirst adducted olefin stream. This stream is enriched in theconcentration of linear alpha olefin over the concentration of linearalpha olefin in the first olefin composition. The alpha olefincomposition comprises a high concentration of linear alpha olefins, andminor amounts of other olefins such as linear internal olefin, branchedinternal olefin, and branched alpha olefins. The concentration of theseother olefins are reduced in the linear alpha olefin composition overthe concentration of these other olefins in the olefin composition. Theconcentration of linear alpha olefins in the alpha olefin composition ispreferably at least 90 wt. %, more preferably at least 95 wt. %, basedon the weight of all ingredients in the alpha olefin stream.

Optionally, and preferably, in step oaiv), the alpha olefin compositionis separated and isolated from the dissociated linear polyaromaticcompounds. The alpha olefin composition at this step, is removed fromthe dissociation vessel to form an alpha olefin stream. The alphaolefins may be removed from the dissociation vessel through the overheadof a cracking vessel operated under slight vacuum and at a temperaturesufficient to vaporize the alpha olefins and dissociate the adducts. Ina more preferred embodiment, the removal of alpha olefins is carried outin the same vessel used to carry out the dissociation reaction in stepoaiii).

If desired, the internal olefin stream may be combined with the secondolefin stream, and used for any of the purposes identified below where ahigh concentration of alpha olefin is not critical to the particularapplication. Alternatively, a portion or the whole of combined internalolefin stream/second olefin stream, or a portion or the whole of theindividual second olefin stream and/or internal olefin stream can berecycled back to the feedstock feed entering the first adductingreaction zone.

For purposes of measuring the percentage reduction of a species in astream, the concentration (all concentrations determined on the basis ofthe total weight of all ingredients present in the stream in question)of the species or series of species in question contained in the productstream is subtracted from the concentration of the species or series ofspecies in question contained in the predecessor stream in question, thedifference then divided by the concentration of the same species in thepredecessor stream multiplied by 100. For purposes of measuring the %enrichment of a species in a stream, the concentration of the species orseries of species in the predecessor or feedstock stream is subtractedfrom the concentration of species or series of species in questioncontained in the product stream, the difference then divided by theconcentration of those same species present in the predecessor feedstockstream and multiplied by 100. For purposes of adding together a seriesof species, the sum total of the series in the predecessor stream isadded, and then the sum total of the species in the product stream areadded if the concentration of the particular species is enriched overthat particular species in the predecessor stream, and subtracted if theconcentration of the particular species is reduced from theconcentration in the predecessor stream. The total in the product streamis then compared to the total in the predecessor stream to determinewhether the total of the series in the product stream was enriched orreduced over the sum total in the predecessor stream. The appropriatecalculation mentioned above is then applied depending on whether theseries in the product stream were reduced or enriched.

The Concentration of Species in the First Olefin Composition and FirstSaturated Hydrocarbon Stream Relative to the Concentration of Species inthe Feedstock

In one embodiment, the concentration of all olefins in the firstsaturated hydrocarbon stream are reduced through the process of theinvention by at least 15%, preferably at least 30%, more preferably atleast 40%, over the concentration of all the olefins in the feedstock.

Since the linear polyaromatic compound is more selective towardsadducting with linear alpha olefins relative to other olefins, theconcentration of linear alpha olefins in the first saturated hydrocarbonstream in another embodiment are reduced by at least 30%, morepreferably by at least 40%, most preferably by at least 50%, over theconcentration of linear alpha olefins present in the feedstock stream.

The concentration of saturated hydrocarbon in the first saturatedhydrocarbon stream is enriched over the concentration of saturatedhydrocarbon in the feedstock stream. In an embodiment of the invention,the concentration is enriched by at least 5%, preferably by at least10%, more preferably by at least 20%, and can be enriched by 100-400%,especially when the concentration of saturated hydrocarbon in thefeedstock is low. Generally, the degree of enrichment of saturatedhydrocarbon in the saturated hydrocarbon stream varies inversely withthe concentration of the saturated hydrocarbons in the particularfeedstock employed.

In another embodiment of the invention, the concentration of saturatedhydrocarbons in the first olefin composition is reduced through theprocess of the invention in only one pass by at least 80%, preferably byat least 90%, more preferably by at least 95% over the concentration ofsaturated hydrocarbon in the feedstock, and most preferably by 100%.

The concentration of linear alpha olefins in the first olefincomposition is enriched over the concentration of linear alpha olefinspresent in the feedstock stream. In an embodiment of the invention, theconcentration of linear alpha olefins present in the first olefincomposition is enriched by at least 30%, more preferably by at least40%, most preferably by at least 60%, over the concentration of linearalpha olefins present in the feedstock composition. The process of theinvention can achieve concentrations of linear alpha olefin in theolefin composition higher than 80 wt. %, more preferably at least 90 wt.%.

Further, the concentration of all olefins in the first olefincomposition is enriched over the concentration of all olefins in thefeedstock stream. The degree of olefin enrichment varies inversely withthe concentration of olefins present in the feedstock. In a preferredaspect of this embodiment, the concentration of all olefins in the firstolefin composition is enriched by at least 40%, preferably by at least60%.

The process of the invention is capable of separating olefins fromsaturated hydrocarbons in a feedstock consisting essentially ofsaturated hydrocarbons and olefins, resulting in a concentration ofolefins in the olefin composition ranging from 90% to 100%.

Enrichment and Reduction of Species in the Second Saturated HydrocarbonStream and the Second Olefin Composition Relative to the First SaturatedHydrocarbon Stream

The process of the invention enriches the concentration of saturatedhydrocarbons in the second saturated hydrocarbon stream relative to boththe first saturated hydrocarbon stream and the feedstock. The degree ofenrichment in the second saturated hydrocarbon stream relative to thefirst saturated hydrocarbon stream is preferably at least 5%, morepreferably at least 10%. In general, the degree of enrichment will notbe extremely high at this stage since the first adduction and separationhighly concentrates the amount of saturated hydrocarbon in the firsthydrocarbon stream.

The second olefin composition and stream are enriched in linear alphaolefins over the concentration of linear alpha olefins in the firstsaturated hydrocarbon stream, preferably by at least 50%, morepreferably by at least 100%.

The concentration of internal olefins is also enriched in the secondolefin composition and stream over the concentration of internal olefinsin the first saturated hydrocarbon stream, preferably by at least 20%,more preferably by at least 50%.

The Concentration of Species in the Alpha Olefin Composition andInternal Olefin Stream Relative to the First Olefin Composition

The concentration of linear alpha olefins in the alpha olefincomposition is enriched over the concentration of linear alpha olefinsin the first olefin composition and in the feedstock. In one embodiment,the concentration of linear alpha olefins in the alpha olefincomposition is enriched over the concentration of linear alpha olefinsin the first olefin composition by at least 15%, more preferably by atleast 20%, most preferably by at least 30%. The concentration of allother olefins in the alpha olefin stream are reduced in this embodiment,collectively, by at least 20%, more preferably by at least 30%, mostpreferably by at least 40%, over the concentration of all other olefinscollectively in the olefin composition. Specifically, the concentrationof branched olefins in the alpha olefin stream may be reduced by 60%,more preferably by 75%, and as high as 90% over the concentration of thebranched olefins in the feedstock and the first olefin stream.

The concentration of internal olefins in the internal olefin compositionis enriched over the concentration of internal olefins in the olefincomposition and in the feedstock. In one embodiment, the concentrationof internal olefins in the internal olefin composition is enriched overthe concentration of internal olefins in the first olefin composition byat least 10%, more preferably by at least 15%, and generally up to 40%.The concentration of branched olefins in the internal olefin compositionin this embodiment are enriched by at least 30%, more preferably by atleast 50%, most preferably by at least 70%. The concentration of linearalpha olefins in the internal olefin stream are reduced in thisembodiment by at least 20%, more preferably by at least 30% over theconcentration of linear alpha olefin in the first olefin composition.

To further illustrate the invention, the FIGURE depicts a block flowdiagram in which each of blocks 1, 2, and 3 represent the adduction,separation, and dissociation steps, and lines 1-8 represent the feed andproduct streams into and from each block. Block 1 represents the firstadduction zone, separation zone, and dissociation zone. Block 2represents the second adduction zone, separation zone, and dissociationzone. Block 3 represents the AO adduction zone, separation zone, anddissociation zone. Line 1 represents the composition of the feedstock,Line 2 represents the composition of the saturated hydrocarbon stream,Line 3 represents the first olefin composition stream, Line 4 representsthe second saturated hydrocarbon stream, and Line 5 represents thecomposition of the second olefin composition stream, line 6 representsthe internal olefin composition, line 7 represent the linear alphaolefin composition, and line 8 represents an embodiment wherein thesecond olefin stream and the internal olefin stream are combined.

The modeled mass balances tabulated below prophetically illustrate oneof the embodiments of the invention wherein the recovery of a highconcentration of linear alpha olefins in the olefin composition, andrecovery of internal olefins and alpha olefins from the first saturatedhydrocarbon stream is desirable. Table A tabulates the mass balancebased upon the quantity of each species in a feed and product stream,while Table B presents a mass balance based upon the concentration ofeach species in a feed and product stream. Table A results are reportedas moles/unit time, and Table B results are reported as a mole percentcomposition in each stream. The mass balances are on a calculated basisto illustrate the concept of the invention, and are based upon the useof anthracene as the linear polyaromatic compound and upon theassumptions noted below Table B.

TABLE A 1 2 3 4 5 6 7 Paraffins 0.15 0.15 0.00 0.15 0.00 0.00 0.00(linear/branched) Saturated alkyl 0.15 0.15 0.00 0.15 0.00 0.00 0.00aromatics Saturated oxygenates 0.15 0.15 0.00 0.15 0.00 0.00 0.00 Linearalpha olefins 0.20 0.06 0.14 0.00 0.06 0.06 0.08 Linear 2-olefins 0.100.05 0.05 0.01 0.05 0.03 0.02 2-methyl 1-olefins 0.25 0.22 0.03 0.110.11 0.02 0.00 Total 1.00 0.79 0.21 0.57 0.21 0.11 0.10

TABLE B 1 2 3 4 5 6 7 Paraffins 15% 19% 0% 26% 0% 0% 0%(linear/branched) Saturated alkyl 15% 19% 0% 26% 0% 0% 0% aromaticsSaturated oxygenates 15% 19% 0% 26% 0% 0% 0% Linear alpha olefins 20% 8% 66%   1% 27%  51%  82%  Linear 2-olefins 10%  7% 22%   1% 22%  27% 16%  2-methyl 1-olefins 25% 28% 12%  20% 51%  22%  2%

The mass balances tabulated below prophetically illustrate anotherembodiment of the invention wherein the recovery of higher quantities,albeit at lower concentrations relative to the embodiment above, oflinear alpha olefins in the linear alpha olefin stream is desirable.Table C tabulates the mass balance based upon the quantity of eachspecies in a feed and product stream, while Table D presents a massbalance based upon the concentration of each species in a feed andproduct stream. The mass balances are on a calculated basis toillustrate the concept of the invention, and are based upon the use ofanthracene as the linear polyaromatic compound and upon the assumptionsnoted below Table D.

TABLE C 1 2 3 4 5 6 7 Paraffins 0.15 0.15 0.00 0.15 0.00 0.00 0.00(linear/branched) Saturated alkyl 0.15 0.15 0.00 0.15 0.00 0.00 0.00aromatics Saturated oxygenates 0.15 0.15 0.00 0.15 0.00 0.00 0.00 Linearalpha olefins 0.20 0.03 0.17 0.00 0.03 0.04 0.13 Linear 2-olefins 0.100.03 0.07 0.00 0.03 0.03 0.04 2-methyl 1-olefins 0.25 0.19 0.06 0.100.09 0.05 0.01 Total 1.00 0.71 0.29 0.56 0.15 0.12 0.17

TABLE D 1 2 3 4 5 6 7 Paraffins 15% 21% 0% 27% 0% 0% 0%(linear/branched) Saturated alkyl 15% 21% 0% 27% 0% 0% 0% aromaticsSaturated oxygenates 15% 21% 0% 27% 0% 0% 0% Linear alpha olefins 20% 4% 58%   0% 19%  35%  75%  Linear 2-olefins 10%  5% 23%   1% 19%  26% 21%  2-methyl 1-olefins 25% 28% 19%  18% 63%  39%  4%

Fisher-Tropsch streams contain a variety of difficult to separatespecies, including saturated hydrocarbons, aromatics, oxygenates,internal olefins, branched olefins, and linear alpha olefins. Anadvantage of a Fisher-Tropsch stream is that it contains a mixture ofboth even and odd carbon, and the process of the invention produces astream having even and odd carbon number olefin species at very low tozero amount of saturated hydrocarbons, with high concentrations oflinear alpha olefins. The process of the invention can also provide aFisher-Tropsch olefin composition having a mixture of internal olefinsand/or branched olefins, and linear alpha olefins with low amounts ofsaturated hydrocarbons.

In one embodiment, the process of the invention provides a composition,preferably Fisher-Tropsch derived, comprising odd and even numberedolefins, and the composition has an average carbon number ranging fromC₅ to C₂₀, preferably C₆ to C₁₈, or optionally in the C₆ to C₁₂ range,comprising:

a) at least two linear alpha olefin species having different carbonchain lengths;

b) the two most predominant (on a mole basis) linear alpha olefinspecies of the at least two linear alpha olefin species are each withinthe range of C₆ to C₁₈, or in the case of using a C₆ to C₁₂ feedstock,within that range, inclusive;

c) the two most predominant linear alpha olefin species are present inan amount of at least 20 wt %, preferably at least 30 wt. %, morepreferably at least 40 wt. %, based on the weight of the olefins in thecomposition;

d) cumulatively, the total amount of linear alpha olefins present in thecomposition within said range, inclusive, is at least 40 wt. %,preferably at least 60 wt. %, more preferably at least 70 wt. %, andeven 90 wt. % or more, based on the weight of the olefins in thecomposition;

e) one or more odd numbered olefins within the range present in anamount of at least 10 wt. %, preferably at least 20 wt. %, morepreferably at least 30 wt. %, and even 40 wt. % or more, cumulative;

f) a cumulative amount of aromatics, saturated hydrocarbons, andoxygenates of 5 wt. % or less, preferably 2 wt. % or less, morepreferably 1 wt. % or less, most preferably 0.5 wt. % or less, eachbased on the weight of the composition; and preferably

g) 6 wt. % or less of branched olefins having branching at the C₂ or C₃position relative to the most proximate double bond, more preferably 4wt. % or less, based on the weight of the composition.

In another embodiment of the invention, the above mentioned compositionhas as one of the two most predominant olefin species an odd carbonnumber linear alpha olefin.

In another embodiment of the invention, there is provided a composition,preferably Fisher-Tropsch derived, having an average carbon numberranging from C₆ to C₁₈ comprising at least two linear alpha olefinspecies having different carbon chain lengths within said range,inclusive, at least 50 wt. % of linear alpha olefins, where thecomposition has a most predominant olefin species represented by ncarbon numbers, wherein the next most predominant olefin species haseither n+1 or n−1 carbon numbers; and wherein said composition comprises2 wt. % or less of saturated hydrocarbons; and preferably wherein saidcomposition has branched olefins containing branching at the C₂ or C₃positions, relative to the most proximate double bond, in an amount of 6wt. %, more preferably 4 wt. % or less, based on the weight of thecomposition.

The process of the invention advantageously provides an olefin streamwhich is highly concentrated in olefins, wherein the concentration ofolefins in the olefin composition may be at least 90% and up to 100%olefin purity in the olefin composition.

The olefin composition stream of the invention is useful as a componentin drilling fluids, to react with elemental sulfur to make sulfurizedproducts as extreme pressure agents in metal working fluids, as aco-monomers for the polymerization of polyethylene, as an intermediatein making polyalpha olefins (PAO) used as a lubricant, as a chlorinationfeed to make polychlorinated hydrocarbons in PVC applications, to reactwith hydrogen sulfides to make primary and secondary mercaptans aspharmaceutical intermediates and as additives to modify the propertiesof rubber, as solvents, and as a precursor for the manufacture ofplasticizer alcohols and detergent range alcohols and surfactants, whichmay be derivatized into detergent range sulfates or alkoxysulfates forlaundry liquids and powders, dishwashing powders and liquids, bar soap,shampoo, liquid hand soap, and hard surface cleaners.

The ranges and limitations provided in the instant specification andclaims are those which are believed to particularly point out anddistinctly claim the instant invention. It is, however, understood thatother ranges and limitations that perform substantially the samefunction in substantially the same manner to obtain the same orsubstantially the same result are intended to be within the scope of theinstant invention. The present invention will now be illustrated bymeans of the following illustrative embodiments and examples which areprovided for illustration and are not to be construed as limiting theinvention.

EXAMPLE

To illustrate the concept of the invention, a Fisher-Tropsch streamcomprised of the composition set forth in Table 1 was used as afeedstock. The FT composition was derived by passing syngas over a FTcatalyst and subsequently distilling products in the boiling point rangeof hexyl to undecyl hydrocarbons. This composition was used as the feed.Hydrocarbons in the C₇-C₁₀ were the most abundant.

0.14 moles of anthracene having a 95% purity and 62.5 g of the feedstockwere placed in an autoclave. The total olefin content of the chargedfeed was about 0.15 moles (19.8 g), for an olefin/anthracene molar ratioof 1.1:1. The autoclave was sealed and then purged with nitrogen. Theautoclave was heated to 255° C. for 5.6 hours to form the Diels-Alderadduct between the olefin and the anthracene. The autoclave contentswere stirred during heating.

Once the reaction was complete, the autoclave was cooled to 20° C. Theproduct mixture was transferred to a glass flask and the unreactedolefin, saturated hydrocarbons, and unreacted oxygenates were removed bydistillation as Sat.Str. 1. The composition of Sat.Str. 1 was determinedby gas chromatographic analysis.

The material remaining in the flask consisted of some entrainedsaturated hydrocarbons, unreacted anthracene, and the anthracene-olefinadduct. The flask and its contents were then heated to a temperatureranging from 310-350° C. to dissociate the adduct to anthracene andOlefin 1 product described in Table 1 below. Olefin 1 product wasseparated and isolated from the anthracene by distillation. 9.3 g ofOlefin 1 product was recovered, of which 8.7 grams was olefin. Thecomposition of Olefin 1 product was determined by gas chromatographicanalysis.

The results indicate that Sat.Str. 1 is enriched in saturatedhydrocarbons (alkanes) over the concentration of saturated hydrocarbonsin the feedstock stream, by 24%. The concentration of alpha olefin inthe Sat.Str. 1 stream was reduced by 55% over the concentration of alphaolefin in the feedstock.

Olefin 1 product is greatly enriched in alpha olefin content and overallolefin content over the concentration of alpha olefin and overall olefincontent in the feedstock stream. Olefin 1 product is enriched in alphaolefin content by 202%, and in overall olefin content, Sat.Str. 1 wasenriched by 197% ([(88.21+5.77)−(27.18+4.43)]/(27.18+4.43)×100).

Further, the concentration of saturated hydrocarbon (alkane)in Olefin 1stream was greatly reduced; by 95%. The presence of saturatedhydrocarbons in Olefin 1 product is due to its incomplete removal upondistillation of the unreacted material from the adduct before thedissociation step.

TABLE 1 SEPARATION OF SATURATED HYDROCARBONS FROM OLEFINS INTERNAL ALPHATOTAL ALKANES OLEFINS OLEFINS OXYGENATES UNKNOWNS COMPOSITION WEIGHT (g)(wt. %) (wt. %) (w %) (wt. %) (wt. %) Feedstock 62.5 63.8 4.43 27.183.06 1.45 Sat. Str. 1 44.3 78.25 4.6 12.23 3.01 0.91 Olefin 1 9.3 3.315.77 88.21 2.0 0.81

The concentration of saturated hydrocarbons in Sat.Str. 1 stream wasenhanced, and the concentration of internal olefins in the Sat.Str. 1stream was enhanced, by separating a portion of the internal olefins inSat.Str. 1 stream from the saturated hydrocarbons.

44.3 g of Sat.Str. 1 containing 7.5 g (0.059 moles) of olefin wastreated with 0.034 moles of anthracene for 6 hours at 255° C. in theequipment noted above. The molar ratio of olefin to anthracene was1.7:1. 30.24 g of unreacted material was removed by distillation asSat.Str. 2 stream. The bottoms of the distillation column was thermallydissociated at 310-350° C. as described above. 1.67 g of the resultingOlefin 2 internal olefin stream was removed by distillation from thedissociated anthracene. Each of Sat.Str. 2 and D were analyzed by gaschromatography. The results are reported in Table 2.

Sat.Str. 2, compared to the feedstock stream Sat.Str. 1, was enriched inalkanes by 7.3%. The concentration of internal olefin in Sat.Str. 2,compared to the feedstock Sat.Str. 1 stream, was decreased by 31%.

Olefin 2 was enriched in internal olefins and in alpha olefins over theconcentration of each olefin in the feedstock Sat.Str. 1 stream. Theinternal olefin enrichment as about 98%, and the alpha olefin enrichmentwas about 570%.

TABLE 2 SEPARATION OF INTERNAL OLEFINS FROM SATURATED HYDROCARBONSINTERNAL ALPHA TOTAL ALKANES OLEFINS OLEFINS OXYGENATES UNKNOWNSCOMPOSITION WEIGHT (g) (wt. %) (wt. %) (w %) (wt. %) (wt. %) Sat. Str.44.3 78.25 4.6 12.23 3.01 0.91 1 Feedstock Sat. Str. 30.24 85.04 6.036.54 1.63 0.76 2 Olefin 2 1.67 6.80 9.11 82 1.26 0.83

The Olefin 1 product was also treated in the following manner to enhancethe concentration of alpha olefin. 0.055 moles of anthracene having a95% purity and 9.3 g of the Olefin 1 product were placed in anautoclave. The total olefin content of the charged feed was about0.0.068 moles (8.7 g), for an olefin/anthracene molar ratio of 1.2:1.The autoclave was sealed and then purged with nitrogen. The autoclavewas heated to 255° C. for 6 hours to form the Diels-Alder adduct betweenthe olefin and the anthracene. The autoclave contents were stirredduring heating.

Once the reaction was complete, the autoclave was cooled to 20° C. Theproduct mixture was transferred to a glass flask and the unreactedolefin, saturated hydrocarbons, and unreacted oxygenates were removed bydistillation as Internal Olefin product. The composition of InternalOlefin product was determined by gas chromatographic analysis, andreported below in Table 3.

The material remaining in the flask consisted of some unreactedanthracene and the anthracene-olefin adduct. The flask and its contentswere then heated to a temperature ranging from 250-280° C. to dissociatethe adduct to anthracene and Alpha Olefin product described in Table 3below. Nitrogen gas was swept over the anthracene-olefin adduct duringthe dissociation step to facilitate olefin removal and recovery. AlphaOlefin product was separated and isolated from the anthracene bydistillation. 2.6 g of Alpha Olefin product was recovered. Thecomposition of Alpha Olefin product was determined by gaschromatographic analysis.

TABLE 3 SEPARATION OF LINEAR ALPHA OLEFINS FROM THE OLEFIN 1 PRODUCTINTERNAL ALPHA TOTAL ALKANES OLEFINS OLEFINS OXYGENATES UNKNOWNSCOMPOSITION WEIGHT (g) (wt. %) (wt. %) (w %) (wt. %) (wt. %) Olefin 19.3 3.31 5.77 88.2 2.0 0.81 Feedstock Alpha 2.61 0.00 2.88 96.93 0.050.14 Olefin Comp. Internal 1.78 8.12 12.25 78.53 0.9 0.2 Olefin Comp.

Linear Alpha Olefin product, compared to the feedstock stream Olefin 1,was enriched in alpha olefin by 10%. The concentration of internalolefin in Alpha Olefin product, compared to the feedstock Olefin 1stream, was decreased by 50%.

Internal Olefin product was enriched in internal olefins over theconcentration of internal olefins in the Olefin 1 feedstock by 112%.

What we claim is:
 1. A process for treating a feedstock comprisingsaturated hydrocarbons, internal olefins, and alpha olefins, comprising:a) contacting the feedstock with a linear polyaromatic compound in afirst reaction zone under conditions effective to form a first reactionmixture comprising first linear polyaromatic compound-olefin adducts andsaid saturated hydrocarbons; b) separating said olefin adducts from thesaturated hydrocarbons in the reaction mixture to form a first linearpolyaromatic compound-olefin adduct stream and a first saturatedhydrocarbon stream; si) contacting at least a portion of the firstsaturated hydrocarbon stream with a linear polyaromatic compound in asecond reaction zone under conditions effective to form a secondreaction mixture comprising a second linear polyaromatic compound-olefinadduct and said saturated hydrocarbons; sii) separating said secondlinear polyaromatic compound-olefin adduct from the second reactionmixture in the second reaction zone to form a second linear polyaromaticcompound-olefin adduct stream and a second saturated hydrocarbon stream,wherein the concentration of the saturated hydrocarbons in the secondsaturated hydrocarbon stream is enriched over the concentration ofsaturated hydrocarbons in the first saturated hydrocarbon stream, andthe concentration of the saturated hydrocarbons in the first saturatedhydrocarbon stream is enriched over the concentration of saturatedhydrocarbons in the feedstock; and oi) dissociating said first linearpolyaromatic compound-olefin adducts to form linear polyaromaticcompounds and a first olefin composition comprising alpha olefins andinternal olefins; oai) contacting the first olefin composition with alinear polyaromatic compound in a third reaction zone under conditionseffective to form a reaction mixture comprising linear polyaromaticcompound-alpha olefin adducts and an internal olefin composition; oaii)separating said linear polyaromatic compound-alpha olefin adducts, andoptionally unreacted linear polyaromatic compounds as well, from thereaction mixture in the third reaction zone to form a linearpolyaromatic compound-alpha olefin adduct stream and an internal olefinstream; oaiii) dissociating the linear polyaromatic compound-alphaolefin adducts to form linear polyaromatic compounds and an alpha olefincomposition; whereby the concentration of alpha olefins in the alphaolefin composition is enriched over the concentration of alpha olefinsin the first olefin composition, and the concentration of alpha olefinsin the first olefin composition is enriched over the concentration ofalpha olefins in the feedstock.
 2. The process of claim 1, wherein thefeedstock is contacted with a linear polyaromatic compound at atemperature ranging from 150° to about 290° C.
 3. The process of claim2, wherein the feedstock is contacted with linear polyaromatic compoundat a temperature ranging from about 220° to about 265° C.
 4. The processof claim 1, wherein the molar ratio of olefins in the feedstock tolinear polyaromatic compounds ranges from greater than 0.25:1 to 10:1.5. The process of claim 1, wherein the first linear polyaromaticcompound-olefin adduct is dissociated by heating the linear polyaromaticcompound-olefin adduct to a temperature ranging from about 250° C. to500° C.
 6. The process of claim 5, wherein the first linear polyaromaticcompound-olefin adduct is heated to a temperature ranging from about300° C. to 350° C.
 7. The process of claim 1, wherein the feedstockcomprises a stream derived from a Fisher-Tropsch process.
 8. The processof claim 7, wherein the feedstock comprises from 15 wt. % to 70 wt. %olefin, based on the weight of all ingredients in the feedstock.
 9. Theprocess of claim 8, wherein the feedstock comprises from 15 wt. % to 60wt. % linear alpha olefin, based on the weight of all ingredients in thefeedstock.
 10. The process of claim 1, wherein the amount of all olefinsother than linear alpha olefins in the feedstock ranges from 5 wt. % to45 wt. %, based on the weight of all ingredients in the feedstock. 11.The process of claim 7, wherein the amount of paraffin ranges from 5 to65 wt. % based on the weight of all ingredients in the feedstock. 12.The process of claim 7, wherein the amount of paraffin in the feedstockranges from 65 wt. % to 99 wt. %.
 13. The process of claim 1, whereinthe feedstock comprises oxygenates and aromatics collectively present inthe feedstock in an amount ranging from 5 wt. % to 30 wt. %, based onthe weight of all ingredients in the feedstock.
 14. The process of claim1, wherein the feedstock has an average carbon number ranging fromC₅-C₂₀ and wherein the predominant olefin species in the feedstock iswithin the range of C₅-C₂₀, inclusive.
 15. The process of claim 1,wherein the total concentration of olefins and the concentration oflinear alpha olefins are enriched in the first olefin composition overthe concentration of olefins and linear alpha olefins in the feedstock,and the concentration of saturated hydrocarbons is reduced in the firstolefin composition over the concentration of saturated hydrocarbons inthe feedstock.
 16. The process of claim 1, wherein the first saturatedhydrocarbon stream is enriched in its concentration of saturatedhydrocarbons over the concentration of saturated hydrocarbons in thefeedstock stream.
 17. The process of claim 16, wherein the firstsaturated hydrocarbon stream comprises olefins, and the concentration ofall olefins in the first saturated hydrocarbon stream is reduced by atleast 30% over the concentration of all olefins present in thefeedstock.
 18. The process of claim 1, wherein the first saturatedhydrocarbon stream comprises linear alpha olefins, and wherein theconcentration of linear alpha olefins in the first saturated hydrocarbonstream is reduced by at least 40% over the concentration of linear alphaolefins present in the feedstock stream.
 19. The process of claim 1,wherein the concentration of saturated hydrocarbon in the firstsaturated hydrocarbon stream is enriched by at least 20% over theconcentration of saturated hydrocarbon in the feedstock stream.
 20. Theprocess of claim 1, wherein the concentration of saturated hydrocarbonsin the first olefin composition is reduced by at least 80% over theconcentration of saturated hydrocarbon in the feedstock.
 21. The processof claim 20, wherein the concentration of saturated hydrocarbons in thefirst olefin composition is reduced in one pass by at least 95% over theconcentration of saturated hydrocarbon in the feedstock.
 22. The processof claim 1, wherein the feedstock comprises branched olefins, and theconcentration of branched olefins in the first olefin composition isreduced over the concentration of branched olefins in the feedstock. 23.The process of claim 1, wherein the feedstock comprises linear alphaolefins, and the concentration of linear alpha first olefins in theolefin composition is enriched over the concentration of linear alphaolefins present in the feedstock stream.
 24. The process of claim 23,wherein the concentration of linear alpha olefins present in the firstolefin stream is enriched by at least 30% over the concentration oflinear alpha olefins present in the feedstock composition.
 25. Theprocess of claim 24, wherein the concentration of linear alpha olefinspresent in the first olefin stream is enriched by at least 40% over theconcentration of linear alpha olefins present in the feedstockcomposition.
 26. The process of claim 25, wherein the concentration ofall olefins in the first olefin stream is enriched by at least 60% overthe concentration of all olefins in the feedstock.
 27. The process ofclaim 1, wherein the feedstock consists essentially of saturatedhydrocarbons, oxygenates, aromatics, and olefins, and the concentrationof olefins in the first olefin composition ranges from 90% to 100%. 28.The process of claim 1, wherein the average carbon number of thefeedstock olefins ranges from 6 to 16, and the predominant olefinspecies in the feedstock is within said range, inclusive.
 29. Theprocess of claim 1, wherein the feedstock comprises from 15 wt. % to 60wt. % linear alpha olefin, from 5 wt. % to 45 wt. % olefins other thanlinear alpha olefins, 5 wt. % to 99 wt. % paraffins, and 15 wt. % to 30wt. % oxygenates and aromatics.
 30. The process of claim 1, wherein thelinear polyaromatic compound at each step comprises anthracene and/orbenzanthracene.
 31. The process of claim 1, wherein the linearpolyaromatic compound at each step comprises anthracene having a purityof 75% or more anthracene.
 32. The process of claim 1, wherein thefeedstock comprises a single carbon cut composition.
 33. The process ofclaim 1, wherein the feedstock comprises a single cut C₆, C₈, or C₁₀composition.
 34. The process of claim 1, wherein the concentration ofsaturated hydrocarbons in the second saturated hydrocarbon stream isenriched by at least 5% over the concentration of saturated hydrocarbonsin the first saturated hydrocarbon stream.
 35. The process of claim 34,wherein the concentration of internal olefins in the second saturatedhydrocarbon stream is reduced by at least 20%.
 36. The process of claim1, wherein the concentration of internal olefins in the second olefincomposition is enriched by at least 50% over the concentration ofinternal olefins in the first saturated hydrocarbon stream.
 37. Theprocess of claim 36, wherein the concentration of linear alpha olefinspresent in the second olefin composition is enriched by at least 100%over the concentration of linear alpha olefins present in the firstsaturated hydrocarbon stream.
 38. The process of claim 1, wherein therate of linear alpha olefin recovery in step oaii) ranges from 60% to95%, based on the amount of alpha olefin present in the feedstock. 39.The process of claim 1, wherein the concentration of linear alphaolefins in the alpha olefin composition is enriched by at least 15% overthe concentration of linear alpha olefins present in the first olefincomposition.
 40. The process of claim 1, wherein the concentration oflinear alpha olefins in the alpha olefin composition is enriched by atleast 20% over the concentration of linear alpha olefins present in theolefin composition.
 41. The process of claim 1, wherein theconcentration of linear alpha olefins in the alpha olefin composition isenriched by at least 30% over the concentration of alpha olefins presentin the first olefin composition.
 42. The process of claim 1, wherein theconcentration of all olefins other than linear alpha olefins in thealpha olefin composition are reduced by at least 20% over theconcentration of all olefins other than linear alpha olefins present inthe first olefin composition.
 43. The process of claim 1, wherein theconcentration of internal olefins in the internal olefin stream isenriched over the concentration of internal olefins in the first olefincomposition.
 44. The process of claim 1, wherein the concentration ofinternal olefins in the internal olefin stream is enriched by at least15% over the concentration of internal olefins in the first olefincomposition.
 45. The process of claim 1, wherein the concentration ofbranched olefins in the internal olefin stream is enriched by at least50% over the concentration of branched olefins in the olefincomposition.
 46. The process of claim 1, wherein the alpha olefincomposition comprises 95 wt. % or more of linear alpha olefins.
 47. Theprocess of claim 1, wherein at least a portion of the internal olefincomposition and/or at least a portion of the second olefin compositionis recycled to the feedstock.
 48. The process of claim 1, furthercomprising a step oii) comprising separating the linear polyaromaticcompound formed in step oi) from the first olefin composition.